Odds show how much money you will win, if you bet on an event to happen. The higher the odds are, the more you will win, relative to your stake. Low odds = lower win. High odds = higher win.
Odds are a ratio of your chances of losing to your chances of winning. Using the above raffle example, your chances of losing are 99 (the other tickets) and your chances of winning are 1 (the ticket you purchased). Your odds are 99 to 1.